The detection of land mines and other ordnance on the battlefield has grown in importance with their increased use, not only for military personnel but also for civilians after hostilities have ceased. The need for new approaches and sensors to increase the speed and efficiency of methods to clear mines is an issue that must be addressed. A method to detect metal mines, on top of or buried under dry sand, is demonstrated using the passive detection of naturally occurring millimeter wave radiation (at 44 GHz) emanating from the scene. Metal targets such as mines places above soil, under an open sky, stand out clearly against the soil background when using a millimeter wave radiometer as an imaging device. There are three basic factors that allow this to happen. First, the sky above has a very low brightness temperature (lower than 400 deg K) which means that it acts like a very cold, low power illuminator that bathes the scene with a very low level of millimeter wave radiation. Second, the soil typically has a high emissivity and emits millimeter wave radiation corresponding to its physical temperature (ca. 295 deg K). Third, the metal target has low emissivity, meaning that its own physical temperature is unimportant in terms of appearance in the millimeter wave regime, that what it reflects determines its appearance. These three factors combines flows: the metal target reflects the low level radiation from the sky and looks like a cold object surrounded by the hot soil which is emitting a higher level of millimeter wave radiation. This high contrast (295 - 40 = 255 deg K), combined with typical modern millimeter wave radiometer sensor temperature resolutions of 1 deg K, allows a high signal-to-noise ratio. Measurements indicate the feasibility of detection of metal under at least 3 inches of dry sand.
Passive millimeter wave sensors for detection of buried mines
Passive Millimeterwellenradiometrie für das Erkennen von im Sand vergrabenen Landminen
1995
5 Seiten, 3 Bilder, 3 Quellen
Aufsatz (Konferenz)
Englisch
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